A reliable method for the determination of cadmium in blood and urine has been developed, and the concentrations in normal subjects and in patients with chronic renal failure have been determined. Dependancy on, and variations with, age, sex and smoking habits in both health and disease have been investigated. The increases of blood cadmium levels during dialysis are shown to be due to the contamination produced by the zinc-oxide plasters used in the construction of the dialysis coils. The correlation of cadmium concentrations with renal disorders, and any associated secondary bone diseases is discussed.